Substation telephone set



A. K. GHOSH SUBSTATION TELEPHONE SET May 13, 1941 Filed Jam,- 14, 1937 m@ mw. um. mx

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s w S Y AJOY KUN/lf? @H05/4 PatentedMay 13, 1941 oNireD STATES PATENT OFFICE 'SUBSTATION TELEPHONE lSET Ajcy Kumar Ghosh, Calcutta, India Application January 14, 1937, v'Serial No. 120,5412

In' Great Britain February 3, 1936 L2 Claims.

This invention relates to call 4registering substation telephone sets.

It has been a common practice hitherto' to .instal call registering meters at the exchange no matter what system is used `corresponding to each of the subscribers lines, in the case 'Where the subscribers are charged at' the message rate principle. These meters are at thel exchange, and with the exception in the case of automatic systems, for example in mechanical switching systems, when calls are made by the subscribers, the calling subscribers meters are actuated by an electric impulse given by the operator' at the exchange. Itis claimed by telephone administrations that the meters are actuated only in the cases of effective calls'and not in the case of ineffective calls, such as no reply, engaged wrong connections and in cases of line out of order, service discontinued, number changed and the like. In the automatic system however, the meters record the number of calls quite automatically. At the end of everymonth, whatever be the system, automatic cr-manual, meters are read and bills are made out according to the ratesy fixed.

There are numerous ytypes of exchanges in different countries working on different systems: such as magneto system, common battery system (usually termed C. B. system) semi C. B. system and other systems which are all manual exchange systems and again there is the automatic exchange of which alone there are several systems. The telephone instruments are generally required to be of diierentmechanism to suit different exchange systems. The present invention is primarily concerned with the telephone instruments at the subscribers end, and here mainly deals with the lcommonly adopted system, which is an up to date C. B. system with lamp indicator.

The call counting system, as now existing is absolutely non-automatic, and from the subscribers point of view there is Ileft suflicient room for doubt as to the number of calls recorded by the exchange operators, as the pub-lic cannot know to their satisfaction, Whether the differentiation between eiective and ineffective calls is correctly made in each and every case and whether themeters are unnecessarily advanced by the interested party. Another disy line and its principal object is to provide 'atelephone instrument embodying a'combination of features which will not only enable the whole operation of call-'registering to take place b'efore the eyes of thesubscriber so 'as to leave Ano room 'for suspicion between the public and telephone administrations; but will alsov enable unauthorized or undesired use' of the instrument to be prevented so that the., meter' shall not be advanced for example in the subscribers yabsence.

According to this invention, a telephone instrument is provided with a meter at the subscribers end of the line for registering voutgoing calls,-

means for advancing the meter by one unit before the instrument can be connected to the exchange for the purpose of eiecting an outgoing call, means for retracting the meter by a unit when the call is ineffective and means being provided for the automatic circuit breaking of they armature (of the meter) when the latter is attracted by the electromagnet (of the meter) and further means by which the armarture is retained in this attracted position as hereafter described.

By means of this invention it is possible to simplify to a great extent the call recording work on the .part ofthe exchange operatorsas well as to dispense lwith elaborate call recording equipments at the telephone exchange. Ihe administrations will however have the meters read by their men, every montljnfrom each subscribers instrument. In addition the instrument is easy to manufacture and necessitates no large alteration yin adapting the invention to existing installations. Also a subscriber may detect from the meter to what extent his telephone has been used in his absence and moreover if the subscriber desires he may prevent advancement of the meter by locking the meter controlling rod.

The invention also suitably provides means for indicating whether the line circuit is in order when the receiver is lifted as well for preventing accidental advancement of the meter when conversation is going on. Means may also be provided for effecting flashing independently of the hoolg or cradle.

It is known in the C. B.` system for provision to be made for electrical indications, for example the production of a typical buzzing note in the ear-.piece termed busy tone denotes engaged and a like tone serves for no reply such as is obtained in the automatic telephone system. But as in many cases the public arenot accustomed to such indications, the operators are generally required to inform them orally. It is quite possible to educate the public to these indications and to adopt the electrical indications exclusively so that the operator at the exchange will have no necessity of uttering "no reply or engaged Within the instrument a meter is provided along with such mechanism that correct recording of calls will be evident when the instrument is desired to be used for sending out calls and further in case of an ineffective call, which has already been recorded in the meter, the stepping back of the meter reading by a unit by the subscriber himself can be effected by suitably utilizingr an electrical impulse provided from the exchange to signify such ineffective` call, 'which means the same meter will tick back one unit. The quality and/or character of the impulse can of course be modified, as desired.

Now for stepping back the meter, the utilisation of the electric impulses, given to signify ineffective calls, will be easily possible, provided a steady impulse can be compounded or included with the tone signal impulses. For retraction of the meter however an impulse has to come in all cases from the exchange; and it is best and simplest to provide the steady impulse side by side with the busy-tone as in that case nothing remains to be done separately on the part of the operator for the meter retraction; whereas it would be to the interest of the subscriber to get his due refund by utilising the impulse as soon as available. One way how the busy-tone and the impulse can 'be compounded is hereinafter described.

Also in :case of ineffective calls like number changed, service discontinued or the like where the busy-tone is not provided and where therefore oral information of ineffective calls is necessary, there will be in the instrument such provision that the operator of the line at the exchange can supply the necessary electric impulse to the line on getting an indication by the supervisory lamp; by means of this impulse the meter can be stepped back by one unit. Further there are suitably various mechanical safeguards explained hereinafter which are provided so that neither party can work the meter to the others disadvantage.

It is important also to note that the percentage of ineffective calls is far less, if not insigniflcant when compared with the percentage of effective calls, and again the number of no reply to calls is much less than engagedf While wrong connection is found fairly frequent due to many reasons, and the chance of this falling into the class of ineffective calls is very small because it becomes ineffective only in the case of the right number, next informed, being reported as engaged or no reply. It has been found that ,engaged covers the greatest volume of ineffective calls.Y And again those ineffective calls other than no reply and engaged do not occur more than once or twice per month per subscriber on the average. Only in case of the latter type of ineffective calls, will it be the duty of the operator to utter some word, say retract, along with what is usually uttered to signify those ineffective calls. The subscriber will then push only cnice a certain knob of the instrument to its full extent when the supervisory lamp will be only once on and again "off and nothing more, and then the operator at the exchange will press a key by which a suitable electric impulse can be given to the subscribers line, whereby the meter will be set back by one unit only.

'Ihere is, however, no need of setting back the meter in case of wrong connections until the corrected number is found to be "no reply or engaged Therefore particularly wrong connection does not necessarily come under the ineffective calls. The matter of setting back the meter for the greater number of ineffective calls is as far as the exchange is concerned automatic, and the rest, although negligible, is under the control of the exchange operator. rIfhe registering of the effective calls is entirely automatic. Nobody can or will ordinarily tamper with the meter reading mainly because of the mechanism adopted, and secondly because it is distinctly against the interest of the parties concerned. The meter therefore works impartially and correctly before the eyes of the subscriber.

It may be mentioned here that like registering, the stepping back of the meter can be entirely automatic as far as the exchange is concerned and can be freed from anybodys control if exclusively electrical indications for every class of ineffective calls is introduced. There is also provision made in the instrument whereby the called subscriber cannot claim for retracting y the meter. Therefore any claim for retracting the metermust come from the calling subscriber only. Thus the chance of a fictitious claim for refund is at once removed. Therefore any complaint from the subscribers side regarding the setting back of the meter, can be generally taken by the authorities as true and can be mostly settled then and there if found correct in favour of the subscriber by supplying an impulse. Otherwise the number of such complaints as are disputed can be noted down and if decided in favour of the subscriber can be deducted from his monthly bill. Also the work of the operator is considerably reduced by automatic recording, and the work of setting back the subscribers meter is mostly automatic, the operators duties will be very much less, than under existing conditions and therefore the occasional duty of providing the necessary electric impulse for setting back the meter will not be neglected due to flashing as this will be noticed by the supervisor.

In applying the invention to the existing type of up to date C. B. telephone instruments, there is provided an ear-piece and a microphone as well as an induction coil, one polarised electric ringer with a condenser in series and one switch, which works automatically by the up and down movement of the hook or cradled due to lifting and replacing of the receiver handle or the receiver microphone handle where both are combined. For convenience both receiver handle and receiver-microphone handle i. e. handmicrophone-telephone, will hereinafter be indicatedby the word receiver Generally, the cradle for the last-mentioned type of receiver, stands outside a casing which has a hole or holes at the top of it for the passage of the cradle stem, and this lcasing encloses all the other portions of the instrument inside. A two wire telephone line from the exchange enters into the instrument and is connected with the ringer through the condenser as well as to the receiver through a switch placed in series, which switch remains broken when the receiver is on the cardle. On lifting the receiver the connection of the line with the phone circuit is established and the supply of ringing current i. e. alternatinglcurrent,l if any at that time, is stopped by a relay at the exchange when the called subscriber lifts his receiver.

The instrument raccording to the invention in addition to, the parts of an up to date C. B. instrument, issuitably provide with certain mechanism hereinafter explained, wherein are two knobs each operating' a rod projecting outside the casing.Y i

A. meter andif desired a glass windowv for reading the meterare Valso provided. I

The meter is operated through `one knob and the 'other-knob' operates' or controls, when turned or pushed as, may bev required, a reversing arrangement for stepping yback the' meter by a digitasfhereinafter explained'.

The arrangement for stepping back the meter is electrically. controlled from the exchange eitherautonratically ory by the exchange operator;Y moreover, themechani'sm of the meter is such that theL meter can only be set back one unit l'at' a time and a typical tone gong is provided worked by the armature of the meter to give'a sound at the time of each reversal of the meter. There is' an indicator to give a test of the line before operating the meter. A horseshoe-magnet or electromagnet with a soft iron amature' is' also provided which controls a switch vplaced in series withV the phone circuit. Further, there is a contrivance for drawing the attention of the operator by means of the line lamp or supervisory lamp as the case may be which is donev at present in the ordinary instruments by moving the hook or cradle up and down. The function eiTect-ed by moving the hook or cradle up and down is eiiected according to this invention by means of the secondknob which when pressedoperatesa mechanism to lcause the necessary break andmake of contacts'to the line wire giving necessary indication by flashing, Several safety locking contrivances are also suitably provided, as hereinafter described.

It is to be understood that the whole instrument with the component parts and connections excepting the receiver and microphone and the hook or cradle, may be mounted and entirely enclosed, in a suitable box which can be properly sealed at its opening side to avoid or to detect any tampering inside. The meter reading and the indicator are suitably visible from outside through glassv windows which are provided. At the two sides of the box there will be provided two holes through which the two knobs previously referred to project outside the instrument. The -placing of the two knobs for appearance can be shifted to any convenient position of the instrument, with corresponding changes in the position of themechanism inside, necessary for such shifting. Also, if desired the movable parts may be adopt-ed to limit or increase the play of connected parts to the required extent through means such as levers or otherwise.

The invention is illustrated in the accompanying drawing which is a diagrammatic view of the instrument according to the invention.

In the drawing;

II is a receiver cradle with a stem 2 having four stops or pins 3, 1, 4 and 5 horizontally iixed tothe stem `2 and insulated from it. The pin 5 projects on both sides of the stem and a hole 6 is provided across the stem 2. A bracket or platform 8 with two holes init is suitably xed to thecasing and the platform 8 supports la .suitable spiral compression spring 9' located over it. The stem 2 passes through the spring 9 and one of the holes in the' platform 8 and rests on the top of the spring 9 4by itsA pin 5 andas a result, the `cradle I-has a ltendency to moveup, but is lowered by the weight of the receiver Ia when the latter is placed over ythe cradle I. A'metal iece- I8 with a metal knob I'I fixed at its vtop rrests over aspring I2 ixed onla bracket Ii2a.

An extension rod IIa is fitted and'xed'to the bottom of member I5, therod Illa passes through the bracket lila, and also passes through the other hole in the bracket 8.

The lower bent end of rod I Ia presses over. the end of a lever 51, and the other end of leve-r 51 enters into the hole 61a, in rod 4I, when the member IU reaches its lowest position.

The adjustments of the lever 6I controlling the rod 65 and the adjustment of the control of lever E1 is such that 51 locksdl after 65 is pulled out' of the hole or recess v61 by lever-BI duringth d-ownward movement of stem 2.

@n the rod IIa is a pin IUS which extends over and controls the spring strip I Ill, When I0 rises to close the switch I3, then Ila also rises and so releases the lever 51. The'other. endof rlever-51 now drops out of .the hole 51o by its own weight and releases rod 4 I. l

Further the rod IIa!l passes between the knives of switch 23awthout touching them. I Ib is a metal bush fixed /to rod IIa and insulated from it. f

The position of I Ib is such that it closes s .itch 23a when Ie rises and closes switch VII3.

The wires 8I connects up a call-registering meter 23 through the switch 23a.

The metal piece I!! can only move up `with the stein 2 on removal of both the restraints of the rejecting 3 and rod IG. When the receiver Io is taken ofi the cradle, and when metal piece l0 moves up, it establishes an electrical connec-` tion by knob yII atswitch i3, A horizontal rod Ill mounted in a bracket Illa is fitted with a spring i5, and normally tendsr to project over the horizontal surface ZI of piece I0 to keep the latter depressed, as also is done by pin 3 when the receiver is on the-cradle I. Rod I4 can be moved back to release piece Il) by the longitudinal movement of the meter-advancing rod I5' when the latter is'pressed by its knob I1 The' rod I4 engages with rod Iii by means of a vertical lever I8 having a fulcrum at I9. EitherA rod Illv or pin 3 of the stem 2 or both, will prevent metal piece I8 from rising' up and forming con-' nection at the switch I3; pin 3 releases its restraint on metal piece I0 when the receiver is' piece le to be forced down till I4 extends over the horizontal surface 2l, thus locking piece I!) and cutting off switch I3. It is to be noted that until pin 3 has rst sufciently depressed piece I, the rod I4 will not act, as the rod I4 will not reach the bevelled edge 251.

It should be fur-ther noted that the switch I3 does not lose connection until the rod, I4 reaches'v say half the height of the bevellededge 20. Further as rod I'Li reaches the bevelled edge 29 the.

acti-on of the spring I5 on rod M will cause I 0 to be pressed down to its full extent thus locking Ill in position leaving switch I3 disconnected. The switch I3 therefore can be cut 01T by the subscriber but cannot be reconnected until the meter is again advanced by rod I6. l

It is to be noted that the spring I5 is of such strength that it can work against springs I2 and IIII to depress member I0, till rod I4 extends over the horizontal surface 2l, when I4 reaches the bevelled edge 20. The inner end of rod I6 will just touch the stem 2 of the cradle I when the receiver is on the cradle. The knob I1 cannot be pushed in at all until the receiver is taken off, vand. the hole 6 in the stem 2 is in alignment with or level with the rod I6.

Now the rod I6 tends to move, due to a spring 22, in the direction as shown by the arrow 22a, and metal piece I can only be released to close the switch I3 when two conditions are satised simultaneously, rstly when the receiver is taken off the cradle I and secondly when rod I6 is pushed through hole 6 to operate the lever I3 to cause rod I4 to release metal piece I0; such connection of switch I3 will enable the subscriber to get the exchange, as the line lamp is lit by the connection of the switch I3. In addition to operating rod I4 through lever I8 there is a further function effected by rod I6. Before rod I6 operates lever I8 to release metal piece I0 it has to actuate a ten toothed ratchet wheel 24 of the call-registering meter 23 by a spring controlled pawl 25 attached to rod I6. This movement of the ratchet wheel 24 due to pushing in of rod I6, advances the meter 23 by one digit at its unit place and thus the meter records a call or rather a connection with the exchange. 23 is a type of counting meter having for example four digits and is therefore able to record up to 9999 i. e.v

practically 10,000 calls. The meter is advanced by manual power, as already explained and can be stepped back by electric impulse. ping back is eiected by another similar ratchet wheel 24a xed to the same axle as the wheel 24 but having its teeth inclined in an opposite direction and operated by the movement of a spring pawl 26 xed to the armature 21 of an electromagnet; the latter being worked by electric impulse given to it. Thus the meter can also be set back by one unit when necessary. In addition to this setting back of the meter the armature 21 cuts oil a connection of the switch 29 placed to series with the meter and at the same time strikes a gong 21h by the hammer 21a xed to the armature 21. Thus when the meter is stepped back, a sound is obtained additionally. The armature of the meter retracting an electromagnet is not controlled by a spring and therefore the connection of switch 23 cannot be reestablished automatically. In this way the retracting of the meter more than one unit by several electrical impulses at a time is prevented, and further in addition there is xed a permanent magnet 30 preferably a horse-shoe magnet, but of course in such a position and at such a distance that it does not appreciably interfere with the useful or elective lines-of-force of the retracting electromagnet of the meter i. e. does not affect the function of the latter magnet when same isexcited. The horse-shoe magnet 3IJ, through its armature 69 mounted on an extension rod 210 of the armature 21 of the meter retracting electro-magnet holds such armature 21 in the attracted position of the electromagnet. Thus when the electromagnet is out of action after retracting the meter, the permanent magnet 30 due to the magnetic contact with the armature 69 does not let the latter drop on the switch 29 to form a connection even if the whole instrument is tilted and a jerk given. 'Ihis prevents the meter of the instrument from being fraudulently The steptoy aaaaizi` retracted by local impulse by any venterprisingV subscriber. l

It should be noted that the weight of the armature 21 is such that when it is at the farthest end of its stroke from the electromagnet 28, it cannot turn the wheel 24a by its pawl 26 when the instrument is tilted or shaken. Further to prevent any possibility of tampering like this a pawl 2Gb may be hinged to and freely suspended from a suitable position in the casing in the same plane as and close to the wheel 24; so that if the instrument is tilted, the pawl 2Gb will swing over a tooth of the ratchet wheel 24 arresting any clockwise rotation of the ratchet wheel 24a. Ordinarily however the pawl 26h has no function.

When the meter is once retracted it can only be made t for another retraction after the meter has been advanced again by rod I6, Whereby the armature 21 will take its former position due to the lever 3I attached to rod I6 and pivoted at 3Ia striking the rod 210 and pulling the armature out and forming the connection at switch 29.

32 is the usual polarised electric ringer working on A. C. both ends of which are connected to the line and which is provided with a condenser 33 in series. 34 is an automatic control for switch 35 and consists of a horse-shoe electromagnet 34a having its armature 36 pivoted at 36a. The cores of both 32 and 34a have brass points on them to avoid magnetic contact with their respective armatures. 'I'he armature 36, due to a spring 36a at its pivoted end, ordinarily keeps away from the magnet as shown and the other end of the armature is pointed.

Now 34 is connected with 32 in parallel and therefore this combination of 3 4 and 32 is in series with the condenser 33, before mentioned. Without however combining 34 and 32 and putting one condenser only, they can be independently joined up with the line having one condenser for each in series. The construction and the resistance of the windings of the electro-magnet is such that the strength imparted to the electro-magnet or control 34 is sufficient not only to attract the armature 36 by the usual ringing current, but is also suihcient to attract it down even if some pressure is exerted by bar 40 on its head; but any current of lower intensity than the usual ringing current such as may be generated during the working of the indicator, explained hereinafter, will not be sufficient to attract down the armature 36 and more so when pin 40 presses over 36, even if the ringer 32 responds. A slight tapping of the cradle just at the moment of ringing but not during the interval of ringing will easily allow the armature 36 to be attracted down by the control 34. In this case the special construction and winding of the control 34 as suggested above may be unnecessary.

31 is a metal rod for closing the switch 35 and moves horizontally,- within a xed tube 38 open at both ends. The rea-r portion of the rod 31 protrudes out of rthe tube 38 and to this portion is hinged one end of an L-shape lever 39. The rod 31 has always a tendency to close the switch 35 due to a comparison spring (not shown) housed inside the said xed tube 38, but when the whole instrument is at rest, it is prevented from so doing in rtwo ways; firstly, due to the pin 4 of armature 36 is attracted down, bar le is no longer obstructed by the armatureti.A

At the time of sending out calls the receiver is. taken off the cradle, but although the lever 39 is thus released, the rod 37 is still prevented from closing the switch 35 due to the armature of 3S obstructing its bar 4I! and to get the exchange, the switch I3 must first be closed by pressing knob I'I4 oi" rod It and thus releasing metal piece Iii as already detailed. When receiving calls the ringer 32 will first ring andv as control 34 is connected with 32 in parallel, the armature 33 will' also be attracted at the same time, and now the cradle I being'liftedv due to the removal of the receiver according to the 'general practice, the lever 39 is also released; and the rod'3'i being freed from both its obstructions simultaneously, will at once proceed to close the switchi and the line now comes to the phone circuit and due to a relay at the exchange, both 32 and 34 will bev put out of action. When the conversation is over, and the receiver replaced, the lever 39 is pressedby pin 4 and the rod 3l is pulled out of switch 35 and the armature 35 alsobieing` released, springs back toits previous position.

It should be understood that the release of the armature 35 must not take place after 3l is pulled out of theswitchti, otherwise it would be possible to partially depress the cradle and make a fraudulent call through the switch 35 by again releasing the partly depressed cradle. The construction of the knob of rod 3,7 and of the tips of the switch 35 is such that when the rod 'is pulled, the tips will yield to some extent say 3 or 4 millimetres, due to friction, and after that limit they will retract to break connection, thus delaying a little the opening of the switch 35. Therefore during this pulled-out stage of the tips of the switch 35, the armature SJ-will spring back to its previousposition to lock 4I). The tips of the switch 35 can, while 37 is pulled,-extend forward a little but cannot be pressed backward when the knob of 3'? jumps between them to establish connection. IIhe same effect may 'be achieved by mounting switch 35 on a springy holder. The closing of the switch 35 must also be. effected like the breaking in an abrupt manner, and any known means may be employed for this purpose. Instead of arranging 3l to proceed forward only horizontally it is also possible to make 3l ride a short inclined cam while proceeding forward and drop within the grip of 35, where the cam ends. In that case: the armature 36 may be arranged to play horizontally. When receiver is replaced, 3l recedes horizontally and finally slipsout from under the said cam.

Ringing oi the C. B. telephone bell is generally made intermittent; the reasons beingthat the intermittent ringing is more effective andless annoying than a continuous ring and also this economises electric current. Further, the ringing takes place say for a period of Aone second,

at intervals of two seconds and this is also made to vary according to load Now the armature 36 will also remain attracted for one second and released for intervals of twoseconds. If the rethe interruptor or machines used in the exchange for intermittent ringing purposes. For outgoing inthe line lamp or supervisory lamp as the case may be, due to the tappingin the subscribers instrument. BY Dressing the cradle line lamp is tori. and vby releasing on and when supervisory is to function on and o In this instrument there is providedaseparate contrivance for this purpose, and the cradle I must not be tapped 'as l isdoneaccording to the present practice, as otherwise this will cutoff the connection as if the conversation were duly nished, and, then the connection cannot, be rerestablishedwithout actuatingthe vmeter again. This tapping is done in the present inventionby a push rod 4I and the object of. its mechanism is fourv fold. Firstly, it serves the purpose of flashing, secondly, it does not allow the subscriber to operate thelamp in-V side the instrument andthe other end isy ilattened.' There is in push rod 4I a groove 42 along l its length and the length of the grooveis equal to the maximum horizontal play as may be necessary for push rod 4I and also there is a groove 43: commencing from one end of` the Vstraight groove 42`andV continuing up to say :one-third oi thecircumference of rod 4|. The combination of 42 and 43 therefore resembles an L cut groove which is say 2 mm. deep. In normal position of rody4-I a pin 44 which is iixed to the casing of the instrument, is,y located in the junction of the `groovesli? and. 43 sothat when rod 4I is pushed,

the rod 4I- cannot be turned; similarly when rod 4Igis turned, the same cannot be pushed. The rod 4I works. onk a spiral compression spring 45 but .one end of the spring wire 4t is fixed to` push rod 4I' and the other end isattached tothe support 53.

By this arrangement the spring 45 canbe compressed and releasedand also some torque canbe given to it when necessary. Hence push rod 4I can be either pushed in or turned round and is able to regain its original position when released asV the torque in spring 45 ifthe rod is turned,

' returns it to a position where 44 will be located ceiver is taken oi the cradle during such interval,

the bar 40 will press against the head of Stand the connection in the .switch 35 willtake place as soon as the next ringing starts, i. e. as soon as the armature 3S is attracted. If desired this period oftwo seconds of no response can be easily further lessened by further shortening the-interval of ringing, i. e. by suitable adjustments in at the vjunction of the grooves 42 and 43. y

The parts 46A and 41 are operated by therpush rod 4I. 46 is a leverperpendicularly iixedfto its horizontal fulcrum member 49 andmember 4'I-'is parallelto the rod 4I. On the member 49 Ythere is another'smaller lever 48 perpendicularly fixed to it, such that if the lever 48 is moved by its upper end inthe Vdirection of the length of rod 4I theupper endof the lever 46 will get arotating movement. The upper end of lever 46 is hinged with suitable plug to the Vend of rod 41 which has a metal piece 50 'at its other end for closing the switch If the knob 52` is pushed in, the lever 48 on the member 49 will be moved by a. spring pawl 53a tted to rod 4| and which normally touches near the top end of 48 and consequently lever 46 will move rod 41 so that piece 50 will break the connection of switch 5|. But as the pawl 53a can give only a tangential movement to the top of the lever 48 while pushing the knob 52, a position will be reached when 48 will automatically be released and due to the spring 41a the rod 41 will also return to its original position and the swtch5| will again be connected by metal piece 50. whether rod 4| returns by that time to its original position or not. This can be repeated if necessary. Again the pawl 53a and the lever 48 in addition to their mechanical function, can mutually establish an electrical connection when they are in contact. The pawl 53a and the lever 48 are insulated from the members to which they are attached. In addition to the other connections at the switch 5|, one end of the switch 5| is connected to the pawl 53a by wire 90 and the other end of switch 5| is connected to the lever 48 by wire 9|.

Flashing is elected thus; when the knob 52 is pressed although the connection of switch 5| is broken due to receding of rod 41 and piece 50, still another connection prevails by the contact between the pawl 53a and the lever 48. The rod A 4|, when its knob 52 is suiciently pressed, will release the lever 48, and rod 41 will spring'back to close the switch 5|; thus within the period of releasing the lever 43 and the reaching of rod 41 to close the switch 5|, the switch 5| remains open for a short period and during this period the line will be interrupted and if the line-lamp.

is to function it will be off and if supervisory lamp is to function it will be on. Therefore, on each tapping of the knob 52 the line lamp is off and again on or alternatively when the supervisory lamp is to function instead of the line-lamp, the same will be on and off automatieally; and the process can be repeated over and over again if required. The timing gap can be adjusted by properly selecting the strength of the spring 41a or by some escapement device or by other means so that the opening and closing of the switch 5| cannot be too rapid, as in that case the lamp indication may not be sufficiently effective. To what limit the knob 52 has to be pressed for the indication in question, will be ascertained in the subscribers earpiece by clicks due to the make and break, as well as a further indication at the time when the pawl 53a releases the lever 48 as at this time the flattened end of rod 4| will touch the attened end of rod 55 which is held in position by a compression spring 92 which is stronger than 45. With some further pressure therefore on the knob 52 the rod 55 can also be pressed. Now the other end of the rod 55 is a metal knob 55a which can close the switch 56 placed in series withV the switches 23a and 29 but the spring 92 always tends to keep rod 55 away from the switch 56.

A lever 58 of a similar nature to 39 already described, operates the switch 69 but there is a difference in the construction of the two levers in that the spring action of the lever 58 is in the opposite direction to that of 39 and therefore the knob 58a of lever 58 always tends to break the connection of the switch 60 'and further there is no bar corresponding to the bar 4|) aforesaid. The lower arm of lever 58 rests normally over the flattened end of rod 55. So long as the lever 58,A

rests over the attened hd of rod 55, th's'witc'h 60 is 'kept closed, as the knob 58a of lever 58 cannot recede. When the rod is pushed by knob 52 which is only possible when calls are made i. e. when rod la rises to release the lever 51,- the connection of switch is not only broken but also rod 55 is locked in the pushed-in position by the lower arm of lever 58 falling and functioning like a pawl, moreover the switch 56 will remain closed, even when rod 4| is released. It will be understood that the switch 56 must be closed simultaneously with the locking of rod 55 by lever 58 and alternatively the switch 56 may be positioned adjacent to the lever 58 so as to be closed directly by said lever 58 in which case the knob 55a is unnecessary.

There is again a three arm lever 6| which enables the lever 58, rod 55 as well as member 65 described later to be brought back to their original position, i. e. to close the switch 60 and open the switch 56 and further when necessary, to open switch 64 and close switch 63. Further the pin 5 of the stem presses on one end of an arm of the lever 6| when the receiver is replaced and in consequence the lower arm of lever 6| pushes the lever 58 and consequently the knob 58a into the switch 60, and at the same time releases rod 55 which disconnects switch 56 and further the third arm of lever 6| lifts when necessary the member 65 which is the control of switches 63 and 64.

The member 65 isa rod shaped like an inverted L, and is placed vertically over rod 4| and is controlled by a spring 66 due to which member 65 presses on rod 4|. In alignment with the lower end of member 65, is the hole or re cess 61 in rod 4|, into which fits the end of the member 65, and the recess 61 is in coincidence with the lower end of member 65 only when rod 4| is say quarter turned from its normal position. There is a thick metal bush or collar 68 fitted to member 65 and insulated from it, or preferably member 65 itself is of insulating material and merely for adding strength both ends of 65 may have metal mountings. When member 65 is resting on rod 4| but not within recess 61 the switch 63 gets connection by pressing over or being in contact with the metal bush 68 but the switch 64 does not get any connection a5 the latter gets connection only when member 65 descends into the recess 61, while the switch 63 then loses connection. The length of the metal bush 68 and its mounting on member 65 is such that during descent of member 65 into the recess 61, the switch 64 gets connection just before switch 63 loses connection, because if there be an interval, the supply of busy tone impulse may discontinue.

The construction of the switch 29 requires to be somewhat different from that of the other switches in the instrument, although some of the other switches can be replaced by a switch of type 29 to serve the same purpose at their respective positions. The switch 29 has two soft contact springs 93, 94 of metal and these two springs obtain connection by the armature 69 which is a metal plate or strip and is mounted i The springs 93, 94 of switch 29 are so soft and the weight of the armature 21 along with its lmiami extension rod 210 and plate 69, although light, is such, that the'springs remain pressed, forming electrical connection and cannot move the armature 21 backj until it isr 'attracted by the electromagnetZ; thisensures Yproper connection and the armature will not get loose by shaking and jerking of the instrument. Some such arrangement is essential as unlike other switches there-is` no additional power to keep 29 properly closed when a current is to pass through it and which is required at the time of retracting the meter; the connection of 23 with 69 breaks only when the full attraction of the armature is effected. y

When the receiver is lifted off its cradle l the yretracting contact -|65 is released by pin 1 disengaging from pin 1a xed to the spring of contact |65. Pin 1a works in a slit |65@ of the tube within which |65 works.

The contact |35 connects to contact $56 to close the line circuit for a moment and then contact |65 retracts to its normal position` y During contact between |65 and |36 when the line is closed fora moment, the galvanometer |01 or other indicator in the line wire shows whether the line of the subscriber is in order or not.

If the line is out of order, the subscriber' must not push knob I1 to advance rod I5 as otherwise the meter will register a call for which he cannot expect retraction.` Again adjustments are such that during reception of calls, 35 is closed before |05 touches |65, so that the ringing current may not pass through the indicator. In the case of automatic instruments however indicators are not essential.

It may further be noticed that the ringer 32 lmay also act somewhat as an indicator when the spring controlled retracting contact |65 functions, even if -the indicator |61 is omitted. As will be realised, the line always remains connected with a battery and the ringer through a condenser remains connected with the line,

and iat this stage if make and break is ef-v 4fected by |135,V a current of pulsating nature (which only can make the ringer respond) will be produced for a moment and the current will pass through the ringing circuit and two distinct sounds will be obtained for each rise of stem 2. Thesound ofthe ringer will be a little short in intensity, as the pulsating current 'so generated is weaker than the usual ringing current adopted.

Additional safety devices are employed as follows:

(a) A device for preventing advancement of the meter through carelessness when the receiver is ou the cradle and rod I6 pushed in the member HJ released i. e. during conversation for cut going calls.

The device is comprised by the spring strip i6 which as already stated is controlled by pin |69 xed on rod Ila attached to the bottom of member ||J.

The strip ||0 enters a slot IH in rod i6 when the latter after releasing the member I0 sets back to rest at its normal position, and thus the rod I6 is locked till the receiver is placed back on the cradle when strip l0 will be pushed down out of slot by pin |69 so as to leave rod I6 released.

(h) A further device for preventing advance-3 ment of thev meter through carelessness while `conversation is going on during incoming calls by locking rod I6. The device comprises a lever H4 fixed to the axis |23 of lever 39 and rod U5 working in a bracket H8. Whenvrnernber 39 is moved to cause'31 to connect switch 35; lever ||4 is also moved by the rotation-of H3 and operates rodvl'l 5 and causes it to enter a slot H6 located in rod |6, thus locking rod I6 till the receiver is placed back on the cradle. When the receiver is replaced, rod 31 and lever 39 move in the opposite sense until ||3 and ||4 cause rod 5 to drop out of slot H6, whereupon rod |6 is released.

The electrical connections are now mentioned with reference to the diagram. e

The two line wires 1l), 1| from the exchange are joined with two connectors Qi and Q2 respectively inside the instrument. The wires 12, 13 of the cord from the receiver microphone handle are joined respectively with two other connectors Qs and Q4 also; inside the instrument are made with insulated wires. Q1 is connected by wire 14 to one end of the condenser 33. The other end of the condenser 33'is connected by wire 1,5 with one end of the ringer 32, and the same end of the condenser is also connected with one end of automatic vcontrol 34 by wire 16. The remaining terminals of 32 and 34, are connected with Q2 by wires 11 and 18 respectively. Again Q2 is `connected with Q3 bywire 13 and Q4 is connected bywire 80 with one end of switch 35, which endl and switch |3, switch 63, switch 66, switch 5|, switch 56, switch 23a, switch 29, the meter-electromagnet 28 and Qa are all connected in series by thev wires 8|. Switch 56 and switch 64 are connected in parallel by wires 91Y and 98. The other end of switch 35 is connected by wire 95 and Q1, as well as by wire 36 with one end of switch 5| as shown in the diagram. Also one end of switch 5| is connected by wire Sil with the pawl 53a and the other end of switch 5| is connected with the rod 43 by wire 3| as already stated. Theline may be joined up with the instrument by insulated wires and, unlike the present practice in such a manner that the instrument cannot be disconnected from the line without leaving signs of tampering.'

The working of the instrument according to the invention is as follows:

When a call comes from outside to the subscriber, due to the usual manipulation at the switch board by the exchange operator, aringing current will pass to the called subscribers line; at this stage only the ringer 32 and the control 34 will'function. Supposing the called subscriber is present and he lifts his receiver to attend to the call, the armature 36 being already attracted down and the pin 4 releasing the lever 39,l the knob 31 jumps into the switch35 which is thus closed and the line now comes to the phone circuit and 32 and 34 cease to function. At this stage, the receiver is connected with the line thus: .l

Q1 i. e. wire 10 gets a connection with Q4 through the switch 35 and Q4 through the receiver-microphone connects to Q3 and then Q3 connectsY to Qz by wire 19 and so to the other wire 1| of the line, and no other circuit of the l gains its previous position. uch receiving of calls can be made over and over again, in the same manner as described. From outside therefore, to a called subscriber, this instrument works in the same manner as the ordinary instruments.

Further, unlike the usual telephone, the exchange cannot be obtained by only lifting the receiver from the cradle I. To give indication to the operator by the line-lamp the subscriber to close the Switch I3. At this point it will be noticed that knob I'I cannot be pushed to release the rod I4 until the receiver is lifted and the hole 6 comes into alignment with rod i6 to allow a longitudinal movement of the rod I6. This can only be effected when the maximum upward@ movement of the cradle stem is reached after the receiver is taken off. This maximumupward movement of stem 2 is controlled by a catch 59 fixed to the platform 8 to obstruct pin 5. The

maximum downward movement of the said stem is reached when the receiver is replaced. Due to the closing of switch I3 the subscribers line lamp at the exchange is lit and the attention of the exchange operator is drawn to it and the.l

exchange operator attends to the subscriber in the usual way. The circuit that functions at this stage is Qi through switches 5I, 60, B3, switch I3 and Q4 and through the phone and receiver goes to Qa and so to Q2 and thus the line is closed,` V

as ordinarily the switches 5I, 8U and 63 remain closed. supposing the number asked for is not engaged and the party attends; the conversation goes on and when nished the receiver is simply replaced on the cradle, and the switch I3 is again cut-off and member I0 is locked by the rod I4.

This is an instance of effective call and has been recorded beforehand and the same thing repeats for all eiective calls.

But it is also possible that, whatever be the reason, the number wanted is found diierent from the number obtained which is an instance of wrong connection, and the calling ysubscriber must get the right connection without any charge, i. e. without advancing his meter any more. his receiver, operate the rod 4I i. e. will push knob 52 to draw the attention of the operator and will simply ask for the right number; suppose the right number is available; the conversation is then carried on and when finished the receiver is replaced. Thus the right number is obtained without further charge although the connection was wrong. But if the right number is not available after all i. e. found no reply or engaged, the meter reading will be stepped back a unit as will be presently explained. Now what takes place on pushing the rod 4I by knob 52 is that 41 is pulled out of the switch 5I, breaking one of the two connections of switch 5I but maintaining the other connection i. e. the one formed by the contact of the pawl 53a with the lever 48 and the wires 9U and SI. Knob 52 is then further pressed, until a click is heard in the phone, when for a moment the switch 5I loses both its closing connections when the supervisory lamp will In such case he will, without replacing be on and again "off" as soon as rod 4l springs back to close the switch 5 I. This can be repeated until the opeator responds. At this point it will be noticed that breaking both the connections of the switch 5I, i. e. keeping it open for more than a short period, is not within the power of the subscriber. `Various methods can, however be adopted for this purpose. The provision of such a mechanism i. e. self-closing switch 5I, is particularly necessary as otherwise any number of calls can be made without operating the meter.

The rod 4I when pushed can give indication by the supervisory lamp as already noted and when necessary it can give indication by the line lamp. That is, 4I can cause only a momentary interruption to the line when knob 52 is pressed. It is also quite possible that the number asked for or the corrected number after wrong connection is found to be fno reply or engaged, both of which are ineffective calls. In this case the meter has already recorded the call as it does in cases of eiective calls, although it is now found ineffective. Under the circumstances, if the indication for no reply or "engaged which covers practically all of the ineffective calls, be given electrically, the subscriber whose call has become ineffective, will turn the knob 52 till it is locked by 65 when the meter will tick back one unit and then he will simply replace his receiver, whereby the instrument will be restored to its original position. What takes place during such retraction is that busy-back tone or tone signal goes on in the phone and turning the knob 52 at this stage has the effect of closing the switch 64 and consequently by wires 91, 98, the switch 56, and then breaking the contact of switch 63 as 65 drops into the recess 61, whereby the line gets connected with the meter, as Q1 connects through the switch 64 to the meter and back to Q3 i. e. Q2 and the impulse compounding with the busytone as explained later sets it back by action of pawl 26 one digit. When the receiver is replaced, the lever 68 is pressed by pin 5 and one arm of 6I pulls up 65 and so rod 4I turns back, and the switch 63 becomes closed while switch 64 opens. Thus the retraction of the meter reading by a unit can be entirely independent of the exchange operator if the system of electrical indication is introduced for all other sorts of ineffective calls, in addition to no reply or engaged as mentioned above. It may be mentioned here, as already said, that some modlfication in the busy tone impulse may be necessary to suit the purpose of stepping back of the meter. The busy tone is supplied from the ringing machine and made to pass through a vibrator and the former makes the current intermittent and the latter vibrating; instead of the vibrator induction coils are also adopted for the said tone. During the supply of busy tone therefore, which is obtained several times the necessary retraction is to be effected, while the buzzing goes on in the receiver. But it is known that a vibrating current may not be very suitable for exciting the electromagnet of the meter suiciently to give clear and effective pull to its armature, on which the stepping back of the meter depends. It can however be arranged for the current at the exchange instead of being made intermittent to be made continuous but alternately passed through the induction coil and connected directly to the line; and this alteration may be effected by the ringing machine. The result will be that the current in question, which will of course have suitable voltage to work `the meter, being-direct, i. e. continuous, vwill produce no buzzing in the ear piece Yof Vthe subscriber when the current is Iput-on the line ldirectly, i. e. not through-the induction coil, Vand during this steady --supply of current the retracting mechanism of the meter can be -made'to easily arranged to supply y.the meter retracting impulse to the line say at intervals of S21-y Nilve seconds during all sorts of tone signals.

But if the system of oral Vinformation has to prevail, the operator will have Ito say retract and on getting this indication the subscriber will push 52 further in than .is necessaryior only dashing, and to do this he will haveto exert a little heavier pressure when rod 4I reaches the attened end of 55, .as 55 vis vheld by 'stronger spring. 1When -55 is thus pushed Yby 4I., the -knob 55a at the other end of 55 closes the switch Y5|i and 55 `will be locked in thatjposition by the lever 58, the latter at the same time also breaking the connection of switchf. At this point it will be observed that the operator gets an indication in the supervisory lamp. By .this theoperator will understand that the `line has been put into the meter circuit and then `the operator will give an electric impulse `from some continuous current source, to the -line of the subscriber. current will flow for .example from Q1 to switch 56, and through switches 23a.and 29, and through these to the electromagnet 28 of the meter 23, then to Q3 and so to Q2 which connects tothe other line wire. It -can be .seen that when the meter circuit .is connected .to .the line, rthe phone circuit is cut off at the switch 50 and this `prevents any current, that may be necessary for retracting the meter, from passing into the `earpiece and making unnecessary noise init. 'When the meter is retracted the armature 21 is attracted and as a result connection is broken at the switch 29 and the hammer 21a is caused to strike the gong 21h, thereby giving the subscriber a sound indication and the operator a lamp indication bythe supervisor-y lamp, which latter may indicate to the operator that the meter 'has 'been actually stepped back. It should also be noted that the switch 29 ordinarily remains closed .by the metal strip E9 fitted to the extension rod 21|] of the meter armature 21, as during the actuating of the meter by pawl 25, the lever 3| pushes the extension rod to close the switch 29. In cases of ineffective calls, no reply and engaged etc., the meter can thus also be retracted by control of the operator.

As already stated, a lock is introduced into the instrument in .order to render inoperative the whole mechanism inside the instrument, meant for outgoing calls, only leaving the instrument t to receive calls. This lock comprises a key controlled bolt I 2D and the desired result can be achieved by arresting the movement of. the rod IS while the instrument is at rest by causing the bolt I 20 to engage recess or notch |2I in rod I6 toprevent rod I3 from being pushed in. On such locking of the rod I6 the switchr I3 can not be closed and therefore calls cannot be made, but the switch 35 is not interfered with and therefore the reception of calls is quite possible, as on liftzingthe receiver during ringing, the rod 31 vwill vjump to-closc 3 5, las explained, giving-a yconnection offthephonewith the line. l v I After-the meter is retracted the subscriber has .only to replace the receiver on the cradle and the :stemof thecradle comingdownwill restore Athe instrument'to its-original position, i. e. will out oit-heswitch 56 and-engage the switch 60 by nrovementoi the lever y61|,lever58 .andrknob 58a. Thus ineffective cal-ls are eliminated when fintimated orally and are controlled by the exchange.

It may rbe noticedthat bothinthe case of -oral and :of electrical .indications of ineffective calls when the meter is to be retracted the rod-4I can be turned, lbut it is better in the case of oral indication to Xpush rod 4I as already detailed-and for this reason namely that Ythe operator :may know whether the line is actually put into the meter circuit after the operator says retract as theA supervisory lamp will be once on and oil But in `case of electrical indication it is always better to turn rod 4I, rstlybecause there is no necessity of lamp indication to the operator and secondly` because the line is not interrupted .at

all at switchv5| during transferring thek line from thephone circuit to the meter circuit.

Regarding the telephone instruments that are used under automatic exchange, the present invention can be adapted in them to give greater facility'to the public than at present, of course where call charge system prevails. The automatic instruments supplied -to the 'subscribers consist of the usual set of 'instruments Yfor-C. vB. working, with the additionv of calling kor selector. apparatus for `sending the requisite nelectrieal impulse along thetwo wire lines for operating the mechanism at the central oice. selector mechanism or dial is mounted on :the instrument. The dial is connected to the` mechanism which, -when'operated for getting connection with some number of a subscriber by turning .of the disc, causes, onitsreturn, a number of disconnections `to be made in 'the line circuit corresponding to the amount of. turning. There are 'callreg'istering meters vat the exchange :which can record calls automatically when the called subscriber attends, and there is no question Yof wrong connection if selecting is right. In the case Aoi no reply or engaged, tone signals are obtainable and these can be'utilisedl for retracting meters in the manner hereinbefore described. Butit maybe noticed that some 'simplification of the mechanism here described is possible when includedfin telephone instruments under the automatic system. For-example, the contrivance for drawing the attention of the operator is not required as there is no operator under the mechanical switching system, and so the switches 5I and 69 can be permanently closed and the knives of switch 56 also parts 48, 41, 58, and 55 as also the lower arm of lever 6I which controls lever 58, and longitudinal groove 42 can be omitted. Control 34 and parts that work in conjunction with it may also be omitted and the movement of the dial of the automatic instrument may be made subject to the same two conditions, as necessary in case of manual system sets, for the operation of switch I3. Instead of connecting and disconnecting switch I3, the metal piece I0 may release or fix the dial in the automatic instrument, the purpose of switch I3 being served in the existing way. In the automatic instrument although connection with the exchange is effected, by lifting the receiver still required number cannot be obtained until dialed and during Thel done by closing when necessary the longitudinal groove 42 only i. e. by preventing the movement of rod 4| along its length, so that rod 4| can only be turned to cause the switches 63 and 64 to function.

It may be further possible for the sake of economy of space and ringing current to combine 32 and 34 as one unit. That is, the soft iron yoke |28 of the combined unit can be replaced by say brass and the cores can be a little more extended downward and a light soft iron armature such as 36 can be suitably tted below it having no spring action, i. e. while the combined unit is at rest, the armature falls by its weight and can thus prevent the rod 31 from closing the switch 35 and when the combined unit works, the armature is drawn up and 3T is set free to close switch 35 when the receiver is off the cradle. For the working of the combined unit of course the pin 4U can be tted to 31 so as to project upwardly. The said replacement by a brass yoke will slightly reduce the strength of the cores of the combined unit but that can be compensated for by providing a stronger or saturated inducing permanent magnet in it, in place of the usual inducing magnet. Slightly increased current strength will bring about a satisfactory result.

It is further within the scope of the invention to adopt locally a relay at the subscribers end for supplying a suciently strong current for the retraction of the meter, if the current used for the purpose from the exchange is not suicient or is not effective due to any reason.

The construction of switches can be of various types and the knobs or plates which connect up the switches are made of metal and these metal knobs or plates should be insulated f rom their respective holders so that other metal parts of the instrument cannot be electrified. It is also to be understood that the control 34 may be positioned in various convenient positions with the corresponding change of the necessary parts.

In place of locking the push rod, the switch connecting the instrument to the exchange for lments where the receiver is separated from the microphone and the former is suspended on a spring hook projecting outside the instrument; there the weight of the earpiece and consequently the movement of the hook may be utilised to `serve all the functions of the cradle stem already explained, the hook comprising or being associated with, an equivalent part to the cradle stem. It is further possible to suitably t up this invention to the existing types of sets as separate attachments.

Having now particularly described and ascertained the nature of my said invention and in what manner the same is to be performed, I declare that what I claim is:

1. In a telephone system the combination of a subscribers telephone set including a transmitting and a receiver unit capable of being electrically connected to an exchange, a receiver, a support for the receiver, circuit closing means actuated by the receiver support adapted to connect and disconnect the unit with the exchange, a toll meter located in the unit for registering outgoing calls, manually actuated means for advancing the meter one -digit after the receiver is raised to connect the unit with the exchange, a push rod having a switch closing member adapted to close a switch and adapted when closed to signal the exchange when a call is not completed through the exchange, said last mentioned means adapted to close a circuit, and means at the exchange for retracting the meter one digit through said closed circuit when the "call" through the exchange is not completed.

2. In a telephone system the combination of a subscribers telephone set including a transmitting and a receiver unit, a receiver, a toll meter on the unit for registering the outgoing calls, means on the unit for advancing the meter one digit when the receiver is raised and means on the unit independent of the operation of the hand set for signalling the exchange when a call is not completed through the exchange, said last-mentioned means adapted to close a circuit and means at the exchange through said last-named circuit for magnetically retracting the meter one digit through said closed circuit when the call through the exchange is not completed.

AJ OY KUMAR GHOSH. 

